title: Square and rectangular symmetry tiles from bulk and thin film 3-miktoarm star terpolymers.
abstract: The directed self assembly of a 3-miktoarm star terpolymer (polyisoprene-arm-polystyrene-arm-polyferrocenylethylmethylsilane (3μ-ISF)) into a (4.8²) square symmetry Archimedean tiling pattern is described. Bulk samples of 3μ-ISF generate equilibrium columnar (4.8²) tile patterns (symmetry p 4 mm) on annealing, which is preceded by a metastable c 2 mm centered rectangular structure. In contrast, in thin films of 3μ-ISF blended with PS homopolymer, the c 2 mm phase is stable with columns oriented out of plane when the film thickness is below 50 nm. However, the 3μ-ISF/homopolymer blend rapidly forms a p 4 mm symmetry when the film thickness is ∼80 nm, with grain sizes of several μm and excellent order. Defects in the p 4 mm structure are described.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Karim
authors.initials: K
authors.lastname: Aissou
authors.forename: Adam
authors.initials: A
authors.lastname: Nunns
authors.forename: Ian
authors.initials: I
authors.lastname: Manners
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Ross
keywords: 3-Miktoarm star terpolymers; Archimedean tiles; phase transitions; self-assembly; thin films